Conform to the Networking TS by renaming the Streambuf concept
to DynamicBuffer in all places. Values of types meeting the
requirements of DynamicBuffer are renamed to dynabuf.
See:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4478.html#requirements.dynamic_buffers
* Headers renamed
* Formal parameter names renamed
* Template argument types renamed
* Documentation updated
